The invention relates to compositions for application as coatings, primarily to wooden and metal structures and installations. The compositions, which have good fire protection and thermal insulation properties, can be used in construction, the aircraft industry, rail transport, shipbuilding and other fields where wooden and metal structures and installations are found.
One of the known forms of fireproofing compositions comprises compositions based on a foaming system, which foam at high temperatures (250-300xc2x0 C.), forming a thermal-insulation coke layer, the thickness of which is 20-25 times that of the original coating. The coke layer which forms during a fire has high thermal insulation properties, so that it prevents the spread of heat through the protected structure. Foaming fireproofing coatings are very effective, but the compositions known so far have a number of defects.
Most of the known coatings include organic solvents (German Patent No. 2704897, IPC C09D 5/18, 1986, USSR Authorship Certificate No. 452224 C09D 5/18, 1972), which considerably increases the fire risk in applying the coatings, and also makes them more toxic.
To improve their fire resistance, halogen-containing compounds are introduced into the known compositions (German Patent No. 2704897, IPC C09D 5/18, 1986), but this makes the coatings highly toxic, particularly in the conditions of a fire.
Most known compositions contain dicyanodiamide as a gas-former (USSR Authorship Certificate No. 1130586, C09K 21/14, 1983, USSR Authorship Certificate No. 1126584, C09D 5/18, C09D 3/52, C09K 21/14, 1982), which makes them toxic and unacceptable from the ecological point of view.
There is a known composition including amino-containing (melamine-formaldehyde) resin, sodium salt of carboxymethyl cellulose, dicyanodiamide, ammonium phosphate, filler and water (USSR Authorship Certificate No. 1126584, C09D 5/18, C09D 3/52, C09K 21/14, 1982), which does not contain halogen-containing compounds or organic solvents, but which, like most other compositions, contains dicyanodiamide as a gas former, so this too is toxic and ecologically harmful.
Another significant problem with known compositions for fireproofing coatings is the low adhesion of the coating to the surface being protected (wood), which leads to cracks and breaches in the coating, and sometimes even to it peeling off from the surface being protected (USSR Authorship Certificate No. 551436, IPC E04F 13/02, 1975), and thus to a reduction in its heat-resistant and thermal insulation properties.
The closest composition for a fireproof coating to the proposed one in its technical nature and in the results it achieves is a composition including water-soluble urea-formaldehyde resin, para-tret, butylphenolformaldehyde resin, ammonium polyphosphate, polyhydric alcohol (pentaerythritol), triazine derivatives, filler and water (RF Patent No. 2065463, cl. C09D 5/18, 1996).
This composition contains no highly toxic components, but has the following faults. The composition is characterised by low-technology production, which firstly leads to a deterioration in its fireproofing properties, and secondly to unjustified additional energy and material costs. Furthermore, its results are not reproducible.
To produce the known composition, a composition is obtained from triazine derivatives by heating carbamide (for 1-1.5 hours) in the presence of phosphoric acid and its ammonia salt, which is then mixed with the other components of the composition (other than ammonium polyphosphate, kaolin and water) and is ground in a ball mill. The ammonium polyphosphate is added to the composition immediately before its application, without grinding it in the ball mill, which inevitably means that it is unevenly distributed in the composition, causing acute local falls in fire resistance, which is confirmed by data on fire-resistant steel structures: 45.5-49 min. for coating thickness 2.6-2.8 mm (and one priming coat), whereas the standard requirement is 60 min. for a coating thickness of 1.4 mm. It may adhere well due to successful priming, but this is no guarantee of fire resistance, since the coating can still crack at high temperatures. The quite good data on loss of mass in burning are explained by the high thickness of the coating.
A serious fault is the high consumption of the composition when the coating is applied: for wood 0.485-0.515 kg/m2, for metal 3.5 kg/m2. Furthermore, this composition is characterised by a short life: six months without the addition of polyphosphate.
The main aim of this invention is the creation of an ecologically clean and non-toxic composition for a fireproof coating which has both high fire-resistance properties and better adhesion to the surfaces being protected.
Another aim of the invention is the creation of a composition for a fireproof coating, which in addition to the above properties, is also easy to produce and can be stored for a long time.
Another aim of the invention is the creation of a composition for a fireproof coating which has the above properties at a low rate of consumption.
These aims are met by the proposed foaming composition for a fireproof coating, which includes, as the foaming system:
polyhydric alcohol
ammonium polyphosphate
urea
ammonium chloride
boric acid
filler
and resin as a binder.
As well as these components, pigment in quantity 2.0-3.0 parts by weight may be introduced into the foaming system.
The proposed compound was developed on the basis of experimental studies of various non-toxic gas formers and combinations of them. The most effective compositions were those containing pentaerythritol and sorbitol (as the polyhydric alcohol) in combination with ammonium polyphosphate. It was also discovered that the use of boric acid not only raises the efficiency of gas formation, but also increases the strength of bonding to the surface being protected, and prevents cracking of the protective layer in conditions of the effect of high temperatures and fire.
The following can be used as the binder resin, which is introduced into the composition in roughly the same weight percentage as the foaming system:
urea-formaldehyde resin (preferably in the form of a 55-65% aqueous solution);
carbamide resin in the form of an aqueous solution;
epoxy resin with ammoniate hardener;
oligoesterepoxide;
oligoestercyanuratimide;
organosilicon resins;
pentaphthalate and hyphaphthalate resins.